Remove value_query, push into sub&fold class
* tree-ssa-propagate.cc (substitute_and_fold_engine::value_on_edge):
Move from value-query.cc.
(substitute_and_fold_engine::value_of_stmt): Ditto.
(substitute_and_fold_engine::range_of_expr): New.
* tree-ssa-propagate.h (substitute_and_fold_engine): Inherit from
range_query. New prototypes.
* value-query.cc (value_query::value_on_edge): Relocate.
(value_query::value_of_stmt): Ditto.
* value-query.h (class value_query): Remove.
(class range_query): Remove base class. Adjust prototypes.